The present invention relates to the general field of turbomachine combustion chambers. It relates more particularly to an arrangement for a combustion chamber of the type comprising a chamber end wall pierced by at least one circular opening, an injector system associated with the opening, and a deflector mounted on the downstream side of the chamber end wall in the opening.
In general, an annular combustion chamber of a turbomachine comprises two longitudinal annular walls (an inner wall and an outer wall) that are interconnected at their respective upstream ends by a transverse wall that is likewise annular and that forms a chamber end wall. The chamber end wall includes a plurality of circular openings that are regularly spaced apart and in which there are mounted injector systems for injecting an air fuel mixture that is to burn inside the combustion chamber.
The fuel is delivered to the injector system via injectors secured to the casing of the turbomachine and having heads centered on the injector system. Air is introduced into each injector system by means of one or more air swirlers that open out downstream from the fuel injector head. In addition, a downwardly-flared bowl is mounted in each opening so as to ensure that the air/fuel mixture is well distributed in the primary zone of the combustion area. Finally, a deflector mounted in each opening in the chamber end wall on the downstream side thereof serves to provide the chamber end wall with thermal protection against the high temperatures of the gas that results from combustion of the air/fuel mixture in the combustion chamber.
Thermal expansion differences exist between the turbomachine casing to which the fuel injectors are connected and the walls of the combustion chamber. In order to accommodate these expansion differences, it is therefore necessary to provide a certain amount of freedom of movement between the combustion chamber and the injector systems. For this purpose, provision can be made to center the fuel injector heads on a sliding cross-member capable of moving radially relative to the injector system (reference can be made for example to document EP 0 833 107). Alternatively, in certain circumstances, lack of concentricity between the injector and the associated injection system is unacceptable, so expansion differences must be accommodated by sliding the injector system relative to the chamber end wall. The invention relates to an arrangement of that latter type.
Such an arrangement must comply with another constraint. In the event of a break in one of the brazed or welded connections connecting together the component parts of the arrangement, it is essential to ensure that none of these parts becomes detached and falls into the combustion chamber where there is a risk it would damage the high pressure turbine mounted at the outlet from the chamber. In order to counter such an event, it is known to give the component parts of the arrangement a diameter that is greater than the diameter of the opening in the chamber end wall and to mount them from the upstream side of the chamber end wall.
Furthermore, it is common practice to provide the bowl of the injector system with a collar that projects inside the chamber end wall and that extends parallel thereto. The main function of such a collar is to protect the injector system against combustion flames in the event of the injector system being off-centered relative to the chamber end wall. Unfortunately, with an arrangement in which the component parts are mounted from the upstream side of the chamber end wall, the bowl collar that needs to pass through the opening in the chamber end wall necessarily presents a diameter that is smaller than the diameter of the opening. Thus, in the event of the injector system being significantly off-centered relative to the chamber end wall, the bowl collar no longer performs its function of providing thermal protection against combustion flames.